gcc - Compiliert nicht!

#include <stdio.h>

#include <pthread.h>

void *print_char (void *ch)

{

  int i;

  for (i=0; i<10; i++)

    printf ("%c", *(char*)ch);

  return NULL;

}

int main ()

{

  char ch1='-', ch2='*';

  pthread_t p1, p2;

  pthread_create (&p1, NULL, print_char, &ch1);

  pthread_create (&p2, NULL, print_char, &ch2);

  pthread_join (p1, NULL);

  pthread_join (p2, NULL);

  printf ("\n");

  return 0;

}